body {
  margin: 0;
  font-family: Arial, sans-serif;
}

.container {
  display: flex;
  flex-direction: column;
  height: 100vh; /* 100% 视窗高度 */
}

.row {
  flex: 1;
  background-color: #f0f0f0;
  padding: 20px;
  box-sizing: border-box;
}